How do you know the streptokinase will digest fibrin only and not good tissues?

Streptokinase specifically targets fibrin due to its ability to bind to plasminogen, converting it into plasmin, which then digests fibrin in blood clots. This action is selective because fibrin is a component of blood clots, whereas healthy tissues do not contain significant amounts of fibrin. Additionally, the enzymatic activity of plasmin is primarily aimed at fibrin and does not have the same affinity for other tissue components. Thus, while there is a risk of some collateral damage, the primary action of streptokinase is to dissolve fibrin in clots.